Hi,
We are experiencing EIGRP neighbors flapping quite often. The log shows the below message:
000867: Jan 11 09:59:18.252 AWST: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 10: Neighbor 10.100.1.1 (GigabitEthernet0/1) is down: holding time expired
000868: Jan 11 09:59:25.328 AWST: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 10: Neighbor 10.100.1.2 (GigabitEthernet0/1) is down: holding time expired
000869: Jan 11 09:59:57.400 AWST: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 10: Neighbor 10.100.1.1 (GigabitEthernet0/1) is up: new adjacency
000870: Jan 11 10:00:09.824 AWST: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 10: Neighbor 10.100.1.2 (GigabitEthernet0/1) is up: new adjacency
We have one router at the remote site and two routers at the head office. Eigrp configured between all three routers. I have performed the below troubleshooting and I am not able to find the exact cause for EIGRP flapping.
- The logs are not showing that the interface went down, so that’s not the cause for the Neighbor flapping
- All the three devices has an hello interval of 5 seconds and the hold time is not less than the hello time. It’s 3 x times the hello time
- There are no loss of hello packets. I enabled “debug eigrp packets hello” on the remote office router and on the one head office router for 20 minutes. Both routers are sending and receiving hello packets
- Tried pinging the neighbors with small packets and then with a large packet [1450 byte] from remote router and vice versa. No drops
- Also tried pinging the Multicast address 224.0.0.10 from remote router and vice versa. Getting response from the neighbors
- Bandwidth has been set properly on all the device interfaces
- The percentage utilization is not high during business hours. But the traffic peaks to approximately 60 to 70% majority of the days between 1.30AM – 3:00AM in the night during backup. But EIGRP is not flapping during that time.
Any help much appreciated.
Thanks
Nachi
